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Biomedical subjects

C Rubio

Publications and source records attributed to C Rubio.

At least 127 records · Page 7Linked to original sources
PubMed1990

[Low-grade B cell gastric lymphoma originated in mucosa-associated lymphoid tissue. Relationship of tumor cells with the marginal zone and monocytoid B lymphocytes. An immunohistochemical and ultrastructural study].

Seven cases of gastric B-cell low-grade lymphomas were characterized by morphology, immunohistology and electron microscopy. All them were immunophenotyped with a panel of monoclonal antibodies against immunoglobulins and other B-cell determinants. Histologic study of gastric B-cell low-grade lymphomas showed germinal centers of lobated shape and polyclonal nature, mainly polyclonal subepithelial plasma cell (except in one case) and neoplastic interfollicular B-cells of monoclonal character. Light-chain restriction supports the neoplastic nature of gastric lymphoma of low-grade malignancy, a distinctive tumour of extranodal B-cell origin. Interfollicular B-cells share with marginal zone cells a perifollicular localization, morphology and phenotype, suggesting a possible relation between these two cellular subtypes. In two cases, the tumour appears constituted by monocytoid B-lymphocytes (MBL), which suggests a relation of tumoral interfollicular B-cells with this subpopulation.

Adult↗
PubMed1990

Ciliated gastric cells: a study of their phenotypic characteristics.

Ciliated cells are found in the basal segments of antral glands whose superficial segments have undergone intestinal metaplasia. The affected cells resemble antral rather than metaplastic intestinal cells. This impression is supported by the immunohistochemical demonstration of pepsinogen group II production and ultrastructural demonstration of pepsinogen granules in the involved segments. Abnormal ciliogenesis in these cells resembles a possibly reversible change in bronchial epithelium that accompanies stasis of secretion and chronic inflammation. Affected antral cells show an evidence of decreased mitotic activity, but the multiplicity of cilia in each affected cell suggests that they stem from the continuing propagation of centriole-basal bodies.

Cilia↗
PubMed1989

The diagnostic value of combining flexible sigmoidoscopy and double-contrast barium enema as a one-stage procedure.

Results from the consecutive examination of 675 patients using both flexible sigmoidoscopy and a double-contrast x-ray technique were analyzed with special reference to the detection of polyps in the rectum and sigmoid colon. A total of 193 polyps were found. Histological examination of 93 polyps revealed that half of those less than 5 mm in diameter and 93.3% of those more than 6 mm in diameter were adenomas. The x-ray examination failed to detect 44% of the proven adenomas smaller than 5 mm, 35.3% of those 6-10 mm in size, and 16.7% of those larger than 11 mm in diameter. These rates were significantly higher than those of flexible sigmoidoscopy, which had corresponding miss rates of 8, 11.2, and 0%, respectively. The double-contrast barium enema (DCBE) failed to detect every second polyp in the rectosigmoid. Every second polyp in the same region proved to be adenoma. The DCBE combined with flexible sigmoidoscopy gives the most reliable and precise diagnosis of various disorders of the rectum and sigmoid colon.

Adolescent↗
PubMed1989

Bleomycin-kanamycin resistance as a marker of the presence of transposon Tn5 in clinical strains of Escherichia coli.

The aminoglycoside modifying enzyme aminoglycoside 3'-phosphotransferase II (APH(3')II) is encoded for on transposon Tn5 by the aphA gene, in the same operon as the ble gene determining bleomycin resistance. To document this linkage 82 kanamycin-resistant Escherichia coli strains of clinical origin were studied; all 18 isolates presenting bleomycin-kanamycin resistance were shown by an enzymatic assay to produce APH(3')II, and the presence of Tn5 was demonstrated by gene hybridization. Similarly, bleomycin-kanamycin resistance was shown to be linked to APH(3')II production in Salmonella spp. The epidemiology of strains with Tn5-encoded APH(3')II may thus be studied, at least in Escherichia coli, by a simple diffusion test using bleomycin and kanamycin discs.

Bleomycin↗
PubMed1989

The effect of arachidonic acid and its metabolites on acid production in isolated human parietal cells.

The effect of arachidonic acid and its metabolites on the histamine-stimulated acid production in human isolated parietal cells provenient from endoscopic biopsies was examined. 14C-aminopyrine (14C-AP) accumulation in the parietal cells was used for evaluation of acid production. Histamine dose-dependently increased AP uptake. Histamine stimulation (taken as 100% at 10(-5) M) was significantly inhibited by prostaglandin (PG) E2 to 66 +/- 7% at 10(-8) M, 42 +/- 8% at 10(-6) M, and 13 +/- 10% at 10(-4) M (mean +/- SEM, n = 10). PGF2 alpha, PGD2, and PGI2 showed significant inhibitory effects only at very high concentrations (10(-5)-10(-4) M). Leukotriene (LT) B4 and LTC4 were without effect. The basal acid production (taken as 0%) was lowered significantly by 10(-6) M arachidonic acid to -20 +/- 7.4% (p less than 0.02, n = 10), and the histamine-stimulated (10(-6) M) acid production from 100% to 64 +/- 7.2% (p less than 0.001, n = 10). Aspirin (10(-3) M) increased basal (45 +/- 9.6%, p less than 0.001, n = 10) and histamine-stimulated (10(-6) M) acid production (164 +/- 16.3%, p less than 0.001). It is concluded that PGE2, the major product from arachidonic acid metabolism in the human gastric mucosa, is a significant inhibitor of the histamine-stimulated human parietal cell and may, in humans, play a role as a local physiologic inhibitor of acid secretion.

Adult↗
PubMed1988

Monocytoid B-cell lymphoma, a tumour related to the marginal zone.

Monocytoid B-lymphocytes are a B-cell subset present in subcapsular sinuses in some cases of lymphadenitis. We describe a case of lymphoma of this cell type. The tumour shows a distinctive morphology characterized by concentric strands of tumour cells around lymphoid follicles with hyperplastic germinal centres and conserved mantle zones. Electron microscopy of these cells shows short cellular processes as well as moderate development of endoplasmic reticulum. The phenotype of the tumour was monoclonal IgM-kappa, distinct from other node-based B-cell subpopulations and suggesting a possible relationship to the lymphocytes of the marginal zone present peripheral to lymphoid follicles of the spleen. Morphological features that suggest a relationship with hairy cell leukaemia are contrasted by phenotypic differences and the ultrastructural absence of ribosomic lamellar complexes.

Aged↗
PubMed1988

Alternating proliferative capacity in the rat gastrointestinal mucosa. Effects of E2 prostaglandins and indomethacin.

Having previously observed an apparent uneven distribution of proliferating cells in the gastric corporic mucosa of the rat, we examined the mitotic distribution along 8-mm sections of gastric and jejunal epithelia. Metaphases were arrested with vincristine to facilitate mitotic count, and the effects of treatment with a prostaglandin E2 analogue and a cyclooxygenase blocker were examined. Clusters of mitotic figures alternating with non-proliferating areas were observed in the gastric corporic epithelium of control rats. During 4 h mitotic activity was absent over 21% of the corporic mucosa. Extending the examined area to about 240 glands reduced substantially the error of mitotic counts. An uneven distribution of mitoses was found in the antral and jejunal epithelium, but areas without proliferating cells were uncommon. Treatment with the prostaglandin E2 analogue reduced the number of mitosis-free areas in the gastric corpus to 13%, and clusters were less easily identified. The total mitotic count was unaffected by treatment. In the jejunum prostaglandin increased the absolute number of mitoses. The mitotic span was also increased, reflecting the uneven distribution. Indomethacin produced the opposite effects to the prostaglandin analogue, including reduction of epithelial height. Of the gastric corporic mucosa 35% was non-proliferating during the observation period, but the clustering phenomenon was still apparent. Absence of dose relationship was attributed to ulcerogenic actions of high doses of indomethacin. It is concluded that mitoses are unevenly distributed in the upper gastrointestinal epithelium of the rat and that safe estimates of mitotic count require examination of large corporic areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Autotransplantation of colonic tumors into the colonic wall of the rat.

Colonic tumors were induced in Sprague-Dawley rats by weekly subcutaneous injections of 1,2 Dimethylhydrazine (DMH) for 4 months. The animals were thereafter laparotomized and a palpable tumor was transplanted into the same animal in a tumor-free area of the transverse colon. Autotransplanted tumors were considered those tumors growing in the wall of the transverse colon, covered by intact colonic mucosa. The frequency of autotransplanted tumors was 34%. The possibility that autotransplantation may also occur in humans by accident, during procedures to remove a colorectal adenocarcinoma, is discussed.

1,2-Dimethylhydrazine↗
PubMed1987

Persistent and generalized lymphadenopathy: a lesion of follicular dendritic cells? An immunohistologic and ultrastructural study.

An immunohistochemical and ultrastructural study of 14 cases of persistent and generalized lymphadenopathy (PGL), acquired immune deficiency syndrome (AIDS) related, revealed florid follicular hyperplasia, follicular dendritic cell (FDC) lysis, lymphoid follicle invaginations, increased presence of T8 cells in germinal center, immature sinus histiocytosis (monocytoid B-cells), and inversion of T4/T8 ratio in the paracortical area. Electron microscopic examination showed viral particles of morphologic characteristics consistent with human immunodeficiency virus (HIV) virions attached to the processes of FDC in three of the nine cases studied. Lesions of the germinal center dendritic cell network are the cardinal feature of PGL. This finding lends support to the idea of a viral aggression directed against FDC as the cause of disregulation of the B-cells.

AIDS-Related Complex↗
PubMed1987

Cell proliferation of the rat gastrointestinal mucosa after treatment with E2 prostaglandins and indomethacin.

The frequency of arrested mitoses after vincristine injection was studied in the gastrointestinal mucosa of rats treated with either natural prostaglandin E2 (0.2-5.0 mg X kg-1, b.d.), 15-R-15 methyl prostaglandin E2 (2 mg X kg-1, b.d.) or indomethacin (1.0-3.0 mg X kg-1, b.d.). In addition to the mitotic index, morphometric measurements including the mucosal thickness and the thickness of the proliferative and functional zones of the gastric corpus, antrum and jejunum were performed. Natural prostaglandin E2, at the highest dose range, reduced significantly the mitotic index in the gastric antrum. Normal values were found in the gastric corpus and jejunum and in the antrum with the lower doses. The mitotic index was unaffected by treatment with 15-R-15 methyl prostaglandin E2. Natural prostaglandin E2 produced trophic changes (i.e. increased thickness and/or hyperplasia) in the antrum, functional epithelial zone of the gastric corpus and in the jejunum. More pronounced trophic changes were observed in the mucosa of rats treated with the analogue. Indomethacin reduced the mucosal thickness in all examined epithelia and lowered the mitotic index in the jejunum. It is concluded that the trophic effects of E2 prostaglandins on gastrointestinal epithelia are not caused by increased production of new cells. The reduced mitotic index observed in the antral mucosa of prostaglandin-treated rats could be secondary to a negative feedback from the hyperplastic epithelium. The antitrophic effects of the prostaglandin-synthesis blocker (indomethacin) indicates that endogenous prostaglandins may participate in the epithelial cell regulation of the gastrointestinal tract.

Animals↗
PubMed1986

Immature sinus histiocytosis a monocytoid B-lymphoid reaction.

The proliferation of characteristic cells in expanded sinuses and in the perivenular area of the paracortex of lymph nodes with patients with toxoplasmosis, and homosexual and drug abusers with lymphadenopathy is referred to as 'immature sinus histiocytosis' (ISH). In a study of nine cases we have shown that these cells are monocytoid B-cells with an immunological phenotype differing from that of other node-based B-cells. The function of these cells is not known.

B-Lymphocytes↗
PubMed1986

Effect of oral prostaglandin E2 on DNA turnover in gastric and intestinal epithelia of the rat.

The mucosal incorporation and clearance of a DNA precursor was examined in the rat stomach and intestine following oral treatment with natural prostaglandin E2 (PGE2) or 15(R) 15 methyl prostaglandin E2 (Me PGE2). Control groups received vehicle or pentagastrin. After five days of treatment animals were labelled with methyl-3H-thymidine. Groups of rats were killed at 0.75, 24, 72, 96 and 120 h after labelling. Treatments continued until killed. Mucosal scrapings were analysed for radioactivity and DNA. Morphometric measurements were performed and plasma levels of gastrin and somatostatin determined. PGE2 and its stable analogue produced hyperplasia within one week of treatment, in particular of the gastric antrum and changed the incorporation and clearance of radioactive thymidine from gastric and intestinal epithelia. The most consistent finding was a delayed elimination of thymidine from the mucosa, indicating a slowing of the DNA turnover. The DNA synthesis was differently affected along the gastrointestinal tract, being unchanged or reduced in the stomach and moderately increased in the intestine. Prostaglandin treatment was associated with a three- to ten-fold increase of the gastric acid contents and with elevated plasma levels of gastrin and somatostatin. It is concluded that E2 prostaglandins produce hyperplasia of gastric and intestinal epithelia in the rat by prolonging the cell survival time rather than by increasing new cell production. Hypergastrinemia is not a likely mediator of trophic actions of E2 prostaglandins, which develop despite elevated plasma levels of somatostatin.

Administration, Oral↗